Evaporator construction



March 9, 1965 s. F. MULFORD 3,172,824

EVAPORATOR CONSTRUCTION Filed April 25. 1961 5 Sheets$heet 1 M w W L. wN

a l s; w INVENTOR.

SfiewmEMufiml BY g 1-8 gwwdwm ATTORNEYS March 9, 1965 s, MULFORD3,172,824

EVAPORATOR CONSTRUCTION Filed April 25, 1961 3 Sheets-Sheet 2 INVENTOR.

Sl'ewwrfi F. Mug mz BY ATTORNEYS March 9, 1965 s. F. MULFORD EVAPORATORCONSTRUCTION 3 Sheets-Sheet 3 Filed April 25, 1961 d 5w w a Q mk mm mm &N MR Q3 9% 8m 10 A/ All. W M v u m wmm 3 m 3m 5 W W 9 EN 9N mvm mw 4/ 8Nll\ ATTORNEYS United States Patent Q F 3,172,824 EVAPORATOR CGNSTRUCTIONStewart F. Mulford, Falls Church, Va., assignor, by mesne assignments,to Baldwin-Lima-Hamilton Corporation, Philadelphia, Pa., a corporationof Pennsylvania Filed Apr. 25, 1961, Ser. No. 105,358 5 Claims. (Cl.202173) My invention relates to improvements in evaporator constructionfor use in distilling sea water and the like, and more specifically toevaporators of the multi-stage type. Even more specifically, myinvention relates to im provements in flash evaporators having two ormore stages, with the sea water being evaporated or distilled flowingcontinuously from one stage to the next.

In prior constructions of multi-stage flash evaporators, certainproblems have been encountered in attempting to design and construct aparticular evaporator construction for maintaining the proper flow ofsea water to be evaporated or distilled therethrough, while stillmaintaining properly balanced and elficient operating conditions. Thisproblem is due principally to the fact that in multistage ilashevaporators, each subsequent evaporator chamber or stage into which thesea water being evaporated flows, operates under a slightly lowertemperature and pressure condition from the evaporator chamber directlyprior thereto.

It is, therefore, necessary in the design and construction ofmulti-stage flash evaporators that a seal of some form must be providedbetween adjacent chambers while still maintaining a constant flow of seawater to be evaporated between such chambers, in order to prevent theblow-through of vapors between chambers in view of the fact that thedifferent pressure conditions are present. This problem is even moregreatly complicated by the fact that this seal must be maintaineddespite varying pressure conditions between the various chambersresulting from varying temperature conditions of the particularchambers.

If the operating conditions of an evaporator could be exactlypredetermined during the design and construction period thereof and ifthese operating conditions, such as for instance, the temperature of theraw sea water taken into the evaporator construction, would remainperfectly constant this problem would be greatly simplified.Unfortunately, however, the operating conditions of a particularevaporator construction cannot always be exactly predetermined andcalculated and it is impossible in many, if not most cases, to determinebeforehand exactly how a particular evaporator construction willfunction, even if absolutely constant operating conditions wouldprevail. In these cases, this can only be determined after theevaporator is installed and pilot runs have been made. Thus, in priorconstruction it has been necessary after pilot runs of particularevaporator plants to make many alterations in an attempt to adapt theconstructions to the particular conditions present.

This still does not solve the problem, however, in view of the fact thatseasonal changes can regularly change the operating conditions. Forinstance, as seasonal changes take place, the temperature of the raw seawater being taken into the evaporator plant will change, thereby, inmany cases, causing the temperature and pressure of each evaporatorchamber or stage to change and requiring a different rate of flowthrough the plant and between the various chambers. Thus, it isdesirable to provide some means in the evaporator construction andpreferably be tween each of the various chambers thereof for regulatingthe flow of the sea water being evaporated between and into thesechambers. By selective adjustment of such means, therefore, not only canoptimumoperating conditions be provided after original installation of apar- 31,172,824 Patented Mar. 9, i955 ice ticular evaporator plant, butalso further adjustments can be made from time to time in order toadjust for the seasonal changes encountered.

Various attempts have been made to satisfy this want and need, forinstance, by the use of the non-adjustable so-called loop seals betweenthe various evaporator chamers, which seals merely consist of agenerally U-shaped conduit for providing the flow of sea water betweenadjacent chambers with this conduit extending downwardly between theparticular chambers. Thus, by maintaining these U-shaped conduits orloop seals at all times at least partially filled with sea water, it ishoped that a seal between chambers will be maintained for preventing theblow-through of vapors discussed above.

The solution of the problem in this manner, however, has not beensatisfactory in view of the fact that the temperature and pressureconditions can vary as discussed above. Also, since there is noadjustability provided, under many operating conditions such seals willbe completely inoperable. Furthermore, even though these loop sealsmight function under certain varying operating conditions, theparticular flow of sea water between the chambers cannot be maintainedat its optimum condition.

It is, therefore, a general object of the present invention to provide amulti-stage flash evaporator construction which eliminates thedifficulties and solves the problems of the prior constructions asdiscussed above.

It is a primary object of the present invention to provide a multi-fiashevaporator construction in which selectively adjustable means isprovided preferably for each of the individual evaporator chambers forselectively adjusting the flow of sea water into and through theparticular evaporator chamber in order to provide the optimum andbalanced flow conditions for maximum efficiency and operability.

It is a further object of the present invention to provide a mnlti-stageflash evaporator construction in which selectively adjustable variableorifice means are provided between the various evaporator chambersthereof for regulating the flow of sea water through these chambers andpreventing the sea water level in any chamber from dropping below apredetermined minimum level.

It is still a further object of the present invention to provide amulti-stage flash evaporator construction in which selectivelyadjustable orifice means is provided for each of the evaporator chambersthereof in order that, by selective adjustment, a sea water level in aparticular chamber may be provided for preventing blow-through betweenadjacent chambers, yet such sea water level may be maintained at aminimum providing the optimum operating conditions.

It is an additional object of the present invention to provide amulti-stage flash evaporator construction in which selectivelyadjustable means is provided between the various adjacent evaporatorchambers for maintaining a relatively constant level of sea water withina particular chamber despite the variation from time to time of thepressure therein.

Finally, it is an object of the present invention to provide amulti-stage flash evaporator construction satisfying the foregoingobjects in a simple and eflicient manner and at a minimum of expense.

These and other objects are accomplished by the parts, constructions,arrangements, combinations and subcombinations comprising the presentinvention, the nature of which is set forth in the following generalstatement, preferred embodiments of which-illustrative of the best modesin which applicant has contemplated applying the principles-are setforth in the following description and illustrated in the accompanyingdrawings, and which are particularly and distinctly pointed out and setforth in the appended claims forming a part hereof.

In general terms the evaporator construction for distilling sea waterand the like comprising the present invention may be stated as includingshell means in the form of one or more shell members enclosing at leasttwo operably connected flash evaporator chambers which chambers operateunder difierent temperature and pressure conditions but through whichthe feed water or salt water being evaporated flows in a continuous flowpath. Each of said chambers preferably has a feed water portion forreceiving the sea water therein to be evaporated or flashed into vaporand a condensing portion for condensing the vapors flashed, therebyproviding the desired distillate.-

Furthermore, the construction includes selectively adjustable orificemeans communicating between the feed water portions of the two chambersfor directing the flow of sea water between the chamber sea waterportions and being selectively adjustable for maintaining the sea waterlevel in the first chamber at least at a minimum level sufficient toprevent the blow-through of vapors between these chambers through saidorifice means while still maintaining how at all times therethrough. inthe case of a plurality of operably connected shells, each having one ormore operably connected flash chambers therein, the adjustable orificemeans would also be providedbetween the lastchamber or stage ofeachshell and the first chamber of the next operably connected shell forthe same purpose. Further, this variable orifice means may be in manyforms such as, for instance, a selectively adjustable butterfly platelocated Within the orifice or a hinged plate selectively movable toobstruct the orifice or a conical member selectively movable axially atleast partially into the orifice, all of which may be adjusted topartially obstruct the orifice and thereby regulate the flow of seawater therethrough. Furthermore, any one of these forms may be providedwith a selectively adjustable float control, wherein the float willautomaticaily adjust the variable orifice under limited varyingoperating conditions to maintain relatively constant sea water levelcontrol, yet may be selectively adjusted to operate under particularlimits for larger changes of operating conditions.

By way of example, embodiments of the improved evaporator constructionof the present inventionare illustrated iii the accompanying drawingsforming a part hereof, wherein like numerals indicate similar partsthroughout the several views and in which:

FIG. 1 is a fragmentary top plan view of a multi-stage flash evaporatorconstruction incorporating the principles of the present invention;

FIG. 2, a fragmentary side elevation of the multi-stage flash evaporatorconstruction of FIG. 1;

FIG. 3, a fragmentary end elevation of the multi-stage evaporatorconstruction of FIG. 1; I

7 FIG. 4, an enlarged fragmentary view, part in elevation and part insection, showing a portion of the interior of the lowest temperatureshell looking in the direction of the arrows 44 in FIG. 1;

FIG. 5, a partially diagrammatical sectional view looking in thedirection of the arrows 5-5 in FIG. 4;

FIG. 6, an enlarged fragmentary sectional view, part in elevation,looking in the direction of the arrows 6-6 in FIG. 4;

FIG. 7, a view similar to FIG. 6 showing a second embodiment of thepresent invention;

FIG. 8, an enlarged fragmentary sectional view, part in elevation, takenparallel to the longitudinal length of one of the shells andillustrating a third embodiment of the present invention;

FIG. 9, a view similar to FIG. 8 illustrating another form of the thirdembodiment of the present invention;

PEG. 10, a view similar to FIG. 8 illustrating a fourth embodiment ofthe present invention; and

FIG. 11, a view similar to FIG. 8 illustrating a fifth embodiment of thepresent invention.

As shown in the drawings, the principles of the present invention areillustrated in a multi-stage flash evaporator construction made up of aseries of generally horizontal longitudinally extending and laterallyadjacent tubular shells 20, each containing three longitudinallyadjacent and operably connected evaporator chambers or stages 21.Furthermore, operably connected within the evaporator construction is anauxiliary salt water heater 22, the operable connection and functionthereof to be hereinafter explained. Also, the entire evaporatorconstruction including the shells 2G and saltwater heater 22 are mountedsupported on a plane surface by the usual structural supporting members23.

As shown in FIG. 4 and stated above, each of the generally horizontalshells 26 contains or encloses three tandem-arranged or longitudinallyadjacent evaporator chambers 2i with each chamber being formed of a feedwater portion 24 and a condensing portion 25. Each of the feed waterportions may be made up of a distribution box 25 into which the incomingsea water, a portion of which is to be evaporated or flashed, enters andoverflows into the remainder of the feed water portion 24 forming thesea water level within the feed water portion, as indicated by thebroken lines 27.

Each of the condensing portions 25 of each of the evaporator chambers21, as illustrated diagrammatically in FIG. 5, includes a vaporseparator 28, through which the vapors flashed from the sea water enterthe condensing chamber 29 to contact the condensing tubes 30 extendingwithin this condensing chamber. The distillate thereby formed from thiscondensing of vapors collects at the lower portion of the condensingchamber 29 forming the distillate level, as indicated by the brokenlines 31, which distillate may be drained from the condensing chamber 29through the usual distillate drain 32.

The sea water entering the feed water portions 24 of the evaporatorchambers 21 enters the particular shell 20 through a conduit 33 andpasses into the distribution box as of the first evaporator chamber ofthat particular shell through the feedwater passageway formed by theorifice 34, which, for this particular evaporator chamber, would'- beformed at the end wall 35 of the particular shell. Furthermore, this seawater passes directly between long'i-- tudinally adjacent evaporatorchambers 21 through simi-- lar orifices 34 formed in the partition ordivision plates- 36 between the adjacent evaporator chambers, in eachcase entering from the orifice 34 into the particular distribution box26 and overflowing into and forming a continuously moving lengthwisebody of feedwater in the remainder of the feed water portion 24 of thatparticular evaporator chamber.

Finally, the sea water leaves the third evaporator chamber 21 of theparticular shell 20 through a conduit 37 and if this particular shell 20were intermediate the evaporator plant the sea water could flow throughconduit 37 into the next shell. In this particular case, however, theparticular shell 20 shown is the last or lowest temperature and lowestpressure shell so that the sea water would flow from this shell eitherto waste, or a portion might be used for recirculation within theevaporator plant in the. usual manner.

As will be hereinafter fully explained in a description, of the generaloperation of the evaporator construction, all of the shells 20 areoperably connected for a continuous flow of sea water from the saltwater heater 22 l-ongitudinally through each of the shells 20, and thisflow is longitudinal through each shell but in opposite longitudinaldirections through laterally adjacent shells. Refer-- ring to FIGS. 1and 2, the shell 20 at the lefthand side of the evaporator plant wouldconstitute the highest tem perature and highest pressure shell, with thetemperature and pressure within the evaporator chambers 21 of the:shells decreasing progressively through this particular shell 20 andprogressively through and between the re.--

mainder of the shells to the last or lowest temperature and pressureshell 20 at therighthand side of the plant.

The condensing medium or cooling medium flowing through the condensingtubes 30 of the condensing chamber 29 of each evaporator chamber 21 israw sea water being preheated preparatory to having a portion thereofevaporated or flashed within the evaporator chambers 21. Further thecondensing tubes 30 of each particular evaporator chamber 21 areoperably connected with the condensing tubes of longitudinally adjacentevaporator chambers and laterally adjacent shells in the usual mannerfor continuous flow through all the condensing tubes.

Thus, the raw sea water first enters the evaporator plant into thecondensing tubes 30 of the lowest temperature and lowest pressureevaporator chamber 21 of the lowest temperature and lowest pressureshell 20, or the lower righthand end of the plant, as viewed in FIG. 1.This sea water being preheated then flows continuously throughlongitudinally adjacent evaporator chambers and between laterallyadjacent shells to finally exit from the highest temperature and highestpressure evaporator chamber 21 of the highest temperature and highestpressure shell 20 through the conduit 38, or from the lower lefthandcorner of the plant as viewed in FIG. 1.

The flow of the raw sea water through the condensing tubes 30 of theevaporator chambers 21, through the shells 20 and between these shells,is therefore exactly longitudinally opposite from the flow of the seawater being evaporated through the shells and chambers, so that the seawater first entering the plant is preheated by passing through thevarious condensing tubes 30 and at the same time constitutes thecondensing medium within these tubes. Furthermore, after passing througheach of the evaporator chambers 21, this preheated sea water then flowsthrough the conduit 38 into the salt water heater 22 and from the saltwater heater through the conduit 39 into the conduit 33 of the first orhighest temperature and pressure shell 20.

Generally the operation of the evaporator plant is therefore as follows.The raw sea water enters the condensing tubes 30 of the lowest pressureand temperatrue evaporator chamber 21 or at the lower righthand cornerof the plant, as viewed in FIG. 1, and this sea water is preheated byforming the condensing or cooling medium within the condensing tubes 30,passing progressively through each of the evaporator chambers 21 tofinally exit through the conduit 38 of the highest temperature andpressure chamber. The salt water then passes through conduit 38 into thesalt water heater 22 where it is heated to the desired temperaturepreparatory to entering the feed water portion 24 of the highesttemperature and pressure evaporator chamber 21 to begin the distillationprocess thereof. The heat added in the salt water heater 22 may bederived from any usual source.

The fully preheated sea water flows from the salt water heater 22through conduit 39 into the conduit 33 of the first shell 20 and fromconduit 33 into the distribution box 26 of the highest temperature andpressure evaporator chamber 21. The sea water overflows the distributionbox 26 into the remainder of the feed water portion 24 of thisparticular evaporator chamber 21, such flow being illustrated by thearrows 40 in FIG. 4.

Within the particular evaporator chamber 21, a certain portion of thesea water is flashed into vapor and rises passing through the vaporseparator 28 into the particular condensing chamber 29, as indicated bythe arrows 41 in FIG. 5. As this vapor contacts the condensing tubes 30within the condensing chamber 29, it gives up a certain portion of itsheat to the sea water being preheated within these condensing tubes andthis vapor therefore condenses at the lower portion of the chamber 29 asdistillate, draining therefrom through the distillate drain 32.

The remainder of the sea water not vaporized within this first chamber,continuously flows through the orifice 34 between this chamber and thenext longitudinally adjacent chamber of this particular shell 20, andthe same process takes place. The sea water as it enters this nextchamber, however, is at a slightly lower temperature and the containedpressure of this next chamber is slightly lower. Thus, in this mannerthe sea water flows continuously through the progressively lowertemperature and lower pressure evaporator chambers 21, longitudinallythrough each of the shells 20 and finally exits from the lowesttemperature and lowest pressure evaporator chamber 21 through theconduit 37 thereof.

In view of the fact that the evaporator chambers 21 operate at differentpressures, with the pressure in each chamber being slightly less thanthe pressure in the preceding longitudinally adjacent chamber, in orderto prevent blow-through of vapors between longitudinally connectedchambers as well as longitudinally connected shells 20, a seal orbarrier must be maintained by the sea water between the longitudinallyadjacent chambers and shells despite the fact that there must becontinuous flow between these chambers and shells. Referring to FIG. 4,the sea water surface elevation level 27 therefore must be maintainedabove the upper edge of the orifices 34 connecting the chambers withadjacent chambers.

Furthermore, the ideal operating conditions are to maintain the seawater levels 27 in the evaporator chambers 21 at a minimum level atwhich this seal may still be maintained. Obviously if the sea waterlevel in a particular chamber becomes too high there is a possibility ofmalfunctioning of the entire evaporator plant.

The sea water level in any given evaporator chamber 21 is dependent on abalancing of the temperature and resultant pressure therein against theflow of sea water to be evaporated therethrough, and as previouslydiscussed, it is extremely difficult if not impossible to exactlypredetermine during the original design and construction of a givenevaporator plant exactly what these conditions will be under operationthereof. Furthermore, seasonal changes resulting in a variation in thetemperature of the raw sea water originally taken into the plant fordistillation can cause the particular operating conditions and thereforethe operating balance of the plant to change, thereby requiring anadjustment in the flow of sea water therethrcugh.

According to the principles of the present invention, therefore, meansis provided at the entrance to and/or exit from each of the evaporatorchambers 21 of the multi-stage evaporator for regulating this flow ofsea water through the passageway into or from that particular chamber.This means is located within the orifice or orifices 34 of theparticular evaporator chamber 21 to be controlled and thereby providesselectively adjustable variable orifice means for preferably each of theevaporator chambers to maintain a sea water level in that particularchamber which is preferably the minimum level required to form a seawater barrier and prevent blow-through of vapors between adjacentchambers.

As shown in FIGS. 4 and 6, this variable orifice means is formed by arectangular plate 42 mounted pivotal about the horizontal center linethereof on a control rod 43. Further, the angle of pivoting of plate 42for increasing or decreasing the obstruction with the orifice 34 iscontrolled from outside the particular shell 20 by the control wheel 44.

As is clear from FIGS. 4 and 6, plate 42 is preferably of smaller sizethan the orifice 34, since it would be unnecessary to ever completelyclose orifice 34 and, as a matter of fact, it is preferable that thisorifice can never be completely closed since this would preventoperation of the entire evaporator plant. It is sufficient that thisplate 42, or whatever variable obstruction is used within the orifice34, be only of suificient size so that when this plate or otherobstruction is in its maximum limiting or flow obstructing position, itwill permit only the minmum flow desired under any conditions and whenin its minimum flow obstructing position it permits the maximum flowever to be desired under any conditions.

This variable orifice means is therefore to be distinguished from, forinstance, a float valve which would completely shut cit flow when aparticular water level is reached and would open for flow as the waterlevel decreased. Here, rather, a selectively adjustable variable orificeis used which will preferably always permit continuous flow therethroughbut may be selectively regulated to determine the continuous flowbetween certain maximum and minimum limits.

The particular construction of plate 42 pivotal about a centralhorizontal axis and mounted, preferably substantially horizontallycentrally within the orifice 34 constitutes such a desired variableorifice construction. Furthermore, it is preferable to provide such avariable onfice construction ahead of or at the inlet to each of theconnected evaporator chambers 21 so that the head of sea water in thepreceding chamber and in subsequent chambers may be individuallyregulated as conditions require.

Thus, a particular multi-stage evaporator may be constructed at the siteof operation and pilot operation thereof begun to determine the exactconditions for such operation. As these conditions are determined, thevarious variable orifices can be individually regulated to provide theproper flow into and from each evaporator chamber 21, to thereby providethe most efiicient operating conditions. Furthermore, as seasonalchanges take place, these variable orifices can be adjusted from time tot me in order to maintain the most efiicient operating conditions.

In FIG. 7, a second construction of variable orifice which likewisecannot be fully closed is shown and in this case a plate 140 of somewhattriangular shape is pivoted at the right angle corner thereof movable tocover a greater or lesser area of the passageway formed by the orifice134. Furthermore, the pivoting of plate 140 may be controlled by usualgear means through the control rod .143 extending outwardly of the shell20 manipulated by the control wheel 144.

The particular form of variable orifice shown in FIG. 7 could be used,one at either side for providing double control of flow into and from aparticular evaporator chamber 21. Also, this particular constructioncould be used in the case of shells 20 having a. central division platesegregating the shell into two laterally adjacent sets or lines oflongitudinally connected evaporator chambers, such general constructionand form of multi-stage evaporator being well known in the art.

In FIG. 8, a third form of non-closing variable orifice means is shownin which case a first orifice 246 is provided in the partition ordivision plate 236 and a second vertical flow orifice 247 is provided ina partition or division plate 248. Division plate 248 is mountedsubstantially vertically midway and horizontally extending within thedistribution box 226 and above the upper edge of the orifice 246. Thus,the passageway between chambers is formed by the partition plates 236and 248, and by the orifices 246 and 247 therethrough, and thispassageway is connected to the feedwater distribution means formed bythe upper part of the distribution box 226;

In this case, the selectively adjustable means for varying the size ofthe orifice 247 and the flow therethrough is a conical member 249,regulated by the control rod 243 extending outwardly of the shell withthe control Wheel 24 4. Thus, by vertically raising and lowering theconical member 249 axially toward and away from the orifice 247, theflow of sea water through this orifice is selectively diminished andincreased. In this manner, the same previously discussed regulation ofthe flow of sea water into and! or from a particular evaporator chamberis provided.

The particular construction illustrated in FIG. 9 is E5 merely avariation of the form shown in FIG. 8, providing a combination of theloop seal hereinbefore discussed with the variable orifice of thepresent invention. As shown, the orifice 259 is provided in the bottomwall 251 of the distribution box 226 and is regulated by the conicalmember 249, control rod 243 and control wheel 244. The loop seal portionis provided with the downwardly extending U-shaped cross sectionpartition wall 252 which directs the flow from the first chamberdownwardly below the bottom wall 251 of the distribution box 226 andthen upwardly through the variable orifice 250 and forming thepassageway between chambers. The advantage here is the provision of amore positive seal between adjacent evaporator chambers which still maybe selectively adjusted through the variable orifice means.

The form of variable orifice means shown in FIG. 10 is a selectivelyadjustable float control non-closing variable orifice means. Theconstruction is generally similar to that shown in FIG. 8 and previouslydescribed, having the same construction of distribution box 326, orifice347, and conical member 349 for obstructing the flow of sea water apredetermined amount through the orifice 347, In this case, however, theconical member 349 is connected through a generally U-shaped control rod353 to a generally spherical float 354.

Control rod 353 is pivoted generally midway of its length for pivotalmovement in a vertical plane through the pivot pin 355. Further and veryimportant to the principles of the present invention is the fact thatfloat 354 is operably connected to the control rod 353 throughadjustment means, such as the threads 356, so that the level of float354 may be adjusted with reference to the control rod 353.

Thus, with this third form of variable orifice means, the float 354 willautomatically regulate the movement of the conical member 349 toward andaway or into and out of the orifice 347, thereby regulating the flow ofsea water through orifice 347 automatically for minor changes in waterlevel of the preceding evaporator chamber. For originally adjusting thesea water flow during the pilot run of the evaporator plant, however, orfor making seasonal adjustments which would be major in character, theadjustment of the'fioat 354 with reference to the control rod 353 wouldbe used, in this case by virtue of the threads 356; Thus, in this thirdform, an automatic variable orifice is shown providing automatic minoradjustments while still permitting selective major adjustments for majorchanges of operating conditions.

Finally a fourth formof variable orifice means is shown in FIG. 11provided by the plate 457 pivoted along its upper edge and along theupper edge of the orifice 446 by the pivot rod 458. Furthermore, thisfourth form may be controlled automatically for minor changes in flow ofseawater similar to the third form previously described, that is,through the control rod 459 and generally spherical float 454. Againfloat 454' is selectively adjustably connected to control rod 459through adjustment means, such as the threads 460.

In this fourth form; similar to the previous forms, the plate 457, evenwhen in its maximum obstructing position as shown, does not fully closethe orifice 446. So in this fourthform, as in the third form, the float454 will automatically adjust the plate 457 and thereby the flow of seawater therethrough between the evaporator chambers for minor changes inoperating conditions, while major changes in'operating conditions arestill regulated through the selective adjustment of float 454 withreference to the control rod 460.

Thus, in every form herein described, variable orifice means is providedin the passageway formed in the partition means between the evaporatorchambers to maintain the optimum condition of flow of the sea waterthrough the evaporator plant. Through selective adjustment of thisvariable orifice means, the sea water level of the body of sea water inthe feed water portions of each of the chambers can be maintainedsufi'iciently high to form a barrier and prevent blow-through of vaporsbetween chambers, while still maintaining this sea water level at aminimum. Further, in certain of the forms illustrated and described, thevariable orifice means is automaticaliy regulated for minor changes inoperating conditions to thereby provide minor changes in sea water flow,while still being provided with selectively adjustable means for makingmajor regulations for major changes in operating conditions.

Still further, it is preferred in every form of the variable orificeconstruction that it be impossible to completely shut off the flowbetween any of the evaporator chambers, but rather only that thevariable orifice means be capable of providing the maximum necesary flowand the minimum necessary flow. Finally, in certain of the forms shown,the selective adjustment of this variable orifice means can beaccomplished from outside of the particular evaporator chambers andevaporator shell, eliminating the necessity of disassembling portions ofthe evaporator construction for making such adjustments and furthermorepermitting such adjustments while the plant is in actual operation.

Although the term sea water has been used in illustrating and describingthe present multi-stage flash evaporator construction, it should beunderstood that the principles of the present invention are equallyapplicable to other forms of salt water or brackish solutions which itmight be desirable to evaporate or distill.

In the foregoing description, certain terms have been used for brevity,clearness and understanding but no unnecessary limitations are to beimplied therefrom, because such words are used for descriptive purposesherein and are intended to be broadly construed.

Moreover, the embodiments of the improved construction illustrated anddescribed herein are by way of example and the scope of the presentinvention is not limited to the exact details of construction shown.

Having now described the invention, the construction, operation and useof preferred embodiments thereof, and the advantageous new and usefulresults obtained thereby, the new and useful construction and reasonablemechanical equivalents thereof obvious to those skilled in the art areset forth in the appended claims.

I claim:

1. In a flash evaporator construction for distilling sea water and thelike in multi-stag generally horizontally disposed, tandem-arrangedevaporator chambers of a type in which feedwater flows continuouslybetween successive stages, in which successively lower internalpressures exist in adjacent stages, and in which the flow of feedwaterbetween adjacent stages must form a feedwater barrier to prevent theblow-through of flashed vapors between said adjacent stages; anelongated generally horizontally disposed tubular shell; partition meansintermediate the ends of the tubular shell dividing the shelllongitudinally into tandem-arranged adjacent evaporator chambers; meansdividing each chamber into a feedwater receiving portion and acommunicating condensing portion for condensing vapors produced byvaporization of part of the feedwater in the chamber receiving portion;the evaporator chamber feedwater receiving portions being provided withinlet and outlet means including a passageway formed in the partitionmeans serving as the feedwater outlet means for one chamber and thefeedwater inlet means for the next lower pressure stage chamber;feedwater distribution means in each chamber receiving portioncommunicating with the inlet means for such chamber; orifice meansforming at least a part of said passageway serving as the feedwateroutlet means for one chamber and the feedwater inlet means for the nextlower pressure stage chamber including feedwater d w regulating means atsaid orifice means adjustable to various orifice means closing positionsregulating the flow of feedwater through the orifice means and to thefeedwater distribution means of said next lower pressure stage chamber,said flow regulating means in maximum orifice means closing positionbeing incapable of completely closing off the flow of feedwater throughsaid orifice means for maintaining a continuous flow of feedwaterthrough said orifice means at all times; and the feedwater distributionmeans in any chamber cooperating with said orifice means and flowregulating means between said chmaber and the next lower pressure stagechamber so as to distribute a body of continuously moving feedwaterlengthwise of the shell in said chamber with a surface elevation levelabove the outlet means for such chamber, thereby separating the internalpressures in the successive chamber stages above the levels of thefeedwater bodies therein and maintaining pressure differentials betweenadjacent chambers; whereby, the surface elevation levels in each chamberof the feedwater flowing continuously through said chamber may bemaintained at a proper operating level and at least at a minimumsuflicient to form a feedwater barrier between adjacent stages forpreventing the blow-through of flashed vapors between said adjacentstages by the adjustment of said flow regulating means at said orificemeans and despite unforeseen operating conditions of the flashevaporator construction at the time of initial installation and despiteseasonal variations in said operating conditions.

2. Flash evaporator construction as defined in claim 1 in which the flowregulating means for said orifice means includes a plate pivotallymounted at said orifice means pivotally adjustable in the direction offlow of feedwater through said orifice means.

3. Flash evaporator construction as defined in claim 1 in which the flowregulating means for said orifice means includes a plate mounted at saidorifice means slidably adjustable in a direction perpendicular to thedirection of flow of feedwater through said orifice means.

4. Flash evaporator construction as defined in claim 1 in which the flowregulating means for said orifice means includes a generally conicalmember positioned with the axis thereof generally parallel to thedirection of flow of feedwater through said orifice means and beingmovable axially into lesser and greater orifice means closing positions.

5. Flash evaporator construction as defined in claim 1 in which the flowregulating means for at least certain of the orifice means are floatcontrolled between lesser and greater orifice closing positions byfloats subject to the feedwater level in the chambers next precedingsaid certain orifice means.

References Cited in the file of this patent UNITED STATES PATENTS 34,484Foss Feb. 25, 1862 35,880 Low July 15, 1862 56,585 Maulsby July 24, 186657,523 Little Aug. 28, 1866 1,782,959 Elliott Nov. 25, 1930 2,759,882Worthen et al Aug. 21, 1956 2,934,477 Siegfried Apr. 26, 1960 2,944,599Frankel July 12, 1960

1. IN A FLASH EVAPORATOR CONSTRUCTION FOR DISTILLING SEA WATER AND THELIKE IN MULTI-STAGE, GENERALLY HORIZONTALLY DISPOSED, TANDEM-ARRANGEDEVAPORATOR CHAMBERS OF A TYPE IN WHICH FEEDWATER FLOWS CONTINUOUSLYBETWEEN SUCCESSIVE STAGES, IN WHICH SUCCESSIVELY LOWER INTERNALPRESSURES EXIST IN ADJACENT STAGES, AND IN WHICH THE FLOW OF FEEDWATERBETWEEN ADJACENT STAGES MUST FORM A FEEDWATER BARRIER TO PREVENT THEBLOW-THROUGH OF FLASHED VAPORS BETWEEN SAID ADJACENT STAGES; ANELONGATED GENERALLY HORIZONTALLY DISPOSED TUBULAR SHELL; PARTITION MEANSINTERMEDIATE THE ENDS OF THE TUBULAR SHELL DIVIDING THE SHELLLONGITUDINALLY INTO TANDEM-ARRANGED ADJACENT EVAPORATOR CHAMBERS; MEANSDIVIDING EACH CHAMBER INTO A FEEDWATER RECEIVING PORTION AND ACOMMUNICATING CONDENSATION PORTION FOR CONDENSING VAPORS PRODUCED BYVAPORIZATION OF PART OF THE FEEDWATER IN THE CHAMBER RECIEVING PORTION;THE EVAPORATOR CHAMBER FEEDWATER RECEIVING PORTIONS BEING PROVIDED WITHINLET AND OUTLET MEANS INCLUDING A PASSAGEWAY FORMED IN THE PARTITIONMEANS SERVING AS THE FEEDWATERD OUTLET MEANS FOR ONE CHAMBER AND THEFEEDWATER INLET MEANS FOR THE NEXT LOWER PRESSURE STAGE CHAMBER;FEEDWATER DISTRIBUTION MEANS IN EACH CHAMBER RECEIVING PORTIONCOMMUNICATING WITH THE INLET MEANS FOR SUCH CHAMBER; ORIFICE MEANSFORMING AT LEAST A PART OF SAID PASSAGEWAY SERVING AS THE FEEDWATEROUTLET MEANS FOR ONE CHAMBER AND THE FEEDWATER INLET MEANS FOR THE NEXTLOWER PRESSURE STAGE CHAMBER INCLUDING FEEDWATER FLOW REGULATING MEANSAT SAID ORIFICE MEANS ADJUSTABLE TO VARIOUS ORIFICE MEANS CLOSINGPOSITIONS REGULATING THE FLOW OF FEEDWATER THROUGH THE ORIFICE MEANS ANDTO THE FEEDWATER DISTRIBUTION MEANS OF SAID NEXT LOWER PRESSURE STAGECHAMBER, SAID FLOW REGULATING MEANS IN MAXIMUM ORIFICE MEANS CLOSINGPORTION BING INCAPABLE OF COMPLETELY CLOSING OFF THE FLOW OF FEEDWATERTHROUGH SAID ORIFICE MEANS FOR MAINTAINING A CONTINUOUS FLOW OFFEEDWATER THROUGH SAID ORIFICE MEANS AT ALL TIMES, AND THE FEEDWATERDISTRIBUTION MEANS IN ANY CHAMBER COOPERATING WITH SAID ORIFICE MEAN ANDFLOW REGULATING MEANS BETWEEN SAID CHAMBER AND THE NEXT LOWER PRESSURESTAGE CHAMBER SO AS TO DISTRIBUTE A BODY OF CONTINUOUSLY MOVINGFEEDWATER LENGTHWISE OF THE SHELL IN SAID CHAMBER WITH A SURFACEELEVATION LEVEL ABOVE THE OUTLET MEANS FOR SUCH CHAMBER, THEREBYSEPARATING THE INTERNAL PRESSURES IN THE SUCCESSIVE CHAMBER STAGES ABOVETHE LEVELS OF THE FEEDWATER BODIES THEREIN AND MAINTAINING PRESSURESDIFFERENTIALS BETWEEN ADJACENT CHAMBERS; WHEREBY, THE SURFACE ELEVATIONLEVELS IN EACH CHAMBER OF THE FEEDWATER FLOWING CONTINUOUSLY THROUGHSAID CHAMBER MAY BE MAINTAINED AT A PROPER OPERATING LEVEL AND AT LEASTAT A MINIMUM SUFFICIENT TO FORM A FEEDWATER BARRIER BETWEEN ADJACENTSTAGES FOR PREVENTING THE BLOW-THROUGH OF FLASHED VAPORS BETWEEN SAIDADJACENT STAGES BY THE ADJUSTMENT OF SAID FLOW REGULATING MEANS OF SAIDORIFICE MEANS AND DESPITE UNFORESEEN OPERATING CONDITIONS OF THE FLASHEVAPORATOR CONSTRUCTION AT THE TIME OF INITIAL INSTALLATION AND DESPITESEASONAL VARIATIONS IN SAID OPERATING CONDITION.